Foundation of a building or installation erected across a ravine extending along a slope

ABSTRACT

A foundation (1) comprises at least one longitudinal wall (4) connected to transversal walls (6) and made arcuate with the camber facing towards a higher ravine point. The foundation (1) is in the form of an arch in the horizontal plane, the end faces of the foundation (1) bearing against the opposite slopes of the ravine.

TECHNICAL FIELD

The invention relates to civil engineering, and in particular, to afoundation of a building or installation erected across a ravineextending along a slope.

BACKGROUND OF THE INVENTION

Masses of such slopes consist of soil layers having non-uniformphysico-mechanical properties characterized by complicated engineeringgeology and hydrogeological conditions are seriously aggravated inseismically active areas where this invention can also be successfullyused.

All methods presently used for the development of territoriescomplicated by ravines or hollows are expensive and require considerableamount of materials and labour effort since the structures of up-to-dateretainment and landslide protection installations, which are part of adevelopment complex, are mainly used to retain in equilibrium masses offill soil used for backfilling of a ravine or hollow or to stabilizelandslide phenomena and are practically not used as foundations forerecting buildings or installations thereupon.

At the same time, there is an evergrowing shortage of land with flatterrain whose lots are primarily used for agriculture and recreation.

The trends in the development of territories complicated by ravines orhollows show that construction is usually carried out by erectingmassive retainment landslide protection installations with thesubsequent backfilling of a ravine or hollow.

Retaining wall is one of the widely used retainment structures. There isa great variety of designs of retaining walls which are made of variousmaterials. In most cases, the retaining walls are used for levellingpurposes, i.e. the retaining walls back-up comparatively small soilmasses from sliding. However, in some cases the retaining walls can bealso used under considerably landslide pressures. A crib-type retainingwall is considered to be one of the most economical designs among thestructures of this type which are capable of taking-up a considerablehorizontal force.

A lattice-type design consisting of vertical reinforced concrete andmetal members extending through landslide soils and secured in stablesoil layers is considered more rational a design than the retainingwalls. The soil between these members performs together with themforming a retainment installation. Among such structures there are piles(precast piles, cast-in-place piles, filled-in piles).

The above mentioned structures are generally loaded by bending. Ifsimilar members do not extend through the entire landslide mass butextend only in a sliding plane area, such constructions will begenerally loaded with shear.

In some cases it may be preferable to use landslide protectionstructures such as so-called anchor-and-stays installations. In thiscase, a slab or a lattice-type structure is placed on the slope surfaceand secured to stable soil layers by means of flexible tie rods cuttingthrough the body of landslide soils.

To protect embankments and excavations, buttress structures are usedwhich extend along a slope and are disposed at some interval from eachother across the slope. The soil between the buttresses form vaultswhich prevent the landslide mass from pressing through. The buttressesare made of stone, concrete and reinforced concrete.

Also known in the art is a landslide protection structure made in theform of piles which are rigidly interconnected by a pilework bearingagainst massive abutments. This structure substantially improves staticperformance of piles and reduces consumption of materials.

Known in the art is a landslide protection structure in which active andlandslide soil pressure is taken-up by a combined retaining wall havingreinforced concrete arch structures. The retaining wall is in the formof a prism of a stone of crystalline rocks on the outer slope of whichthere are horizontal reinforced concrete arches disposed at differentheight and serving to take-up an excessive pressure exerted on the wall.The arches bear against reinforced concrete foundations made in semirockor rock soils of the ravine sides. A disadvantage of this design residesin considerable consumption of materials and high cost caused by thefact that the retaining wall takes-up a landslide pressure only byvirtue of friction between the wall and soil bedrocks so that theretaining wall should be of a considerable cross-sectional area. Toenhance a load-bearing capacity of the retaining wall under slip, it isnecessary that its outer slope be reinforced with reinforced concretearches. Furthermore, a substantial disadvantage of the retaining walldesign resides in underdevelopment of territories complicated by ravinesbecause when this design is utilized it is only possible to backfill theravine with soil which connot be used as a base for a building orinstallation because of large non-uniform settlements which occur inbackfilling. A lot formed upon the ravine backfilling is used not forerection of buildings but for making sporting grounds, parks, etc., thepossibility of using this landslide protection structure as foundationof a building or installation being out of the question.

Known in the art are foundations of buildings or installations erectedacross ravines extending along slopes.

Generally such foundations consist of vertical longitudinal andtransverse walls. When such foundations are erected in ravines, theouter longitudinal wall facing towards a higher ravine point is eitherin contact with the soil of the ravine backfilling and takesup thehorizontal pressure of the backfilling mass or is not in contact withthis backfilling.

In the latter case, slope retainment structures are erected which are inthe form of retaining walls located in front of the outer wall of thefoundation which faces towards a higher ravine point.

In both cases, the soils of the ravine slopes are under the action ofthe inclined component not only of the weight of the soil of the ravinebackfilling but also of the inclined component of the foundation weightand the weight of a buiding erected thereupon.

A substantial disadvantage of such foundations is a considerableshearing action exerted upon weak soils of the ravine bottom which mayresult in a loss of stability of the ravine bottom soils under thebuilding. Because of this, in designing buildings on such slopes theravine backfilling weight acting upon the foundation is taken intoaccount. In order to take-up additional shearing loads acting upon thefoundation, its walls are reinforced or additional retaining walls areerected which results in a considerably higher amount of materials(concrete, steel) required for erection of a foundation and makes itmuch more expensive.

The present invention is based on the problem of providing such afoundation of a building or installation erected across a ravineextending along a slope whose design would make it possible to take-uploads caused by landslide pressure while taking-up loads from a buildingor installation.

SUMMARY OF THE INVENTION

This problem is solved by that in a foundation of a building orinstallation erected across a ravine extending along a slope, comprisingvertical longitudinal and transverse walls, according to the invention,at least one longitudinal foundation wall connected to the transversalwalls is made acruate with the camber facing towards a higher ravinepoint, its end faces bearing against opposite ravine slopes, thefoundation being in the form of an arch in the horizontal plane.

The foundation design according to the invention makes it possible totake-up the load from the building along with the horizontal landslidepressure owing to considerable mass of backfillings of the ravine on theside of the convex portion of the arch. The arch form of the foundationis most effective when the foundation is under the action of ahorizontal pressure since in this case the arch rise has a directionopposite to that of this pressure. When compared to a conventionalretaining wall, the foundation according to the invention is more stabledue to a considerable load from the weight of a building erectedthereupon. Furthermore, the arch form of the foundation as aconstruction bearing against two supports, i.e. opposite ravine walls,makes it possible to transform in the base of the horizontal landslidepressure along the ravine into the transversal pressure facing towardsthe opposite ravine walls. This makes it possible to take-upconsiderable horizontal landslide pressures from the ravine backfillingand eventual seismic action from the building weight.

The design of an arch foundation loaded by compression, which is themost favourable type of load for concrete, makes it possible toconsiderably reduce the amount of materials required in the erection ofa foundation thus lowering its cost.

Furthermore, the above mentioned transformation of load acting upon thefoundation makes it possible to practically eliminate transmission ofthe load from the building to weak soils of the ravine bottom.

In the preferred embodiment of the invention using two arcuatelongitudinal walls having their camber directed towards a higher ravinepoint, the walls are installed in parallel with each other, thefoundation being of a box-shaped cross-section.

Such embodiment of the foundation makes it possible to enhance itsload-bearing capacity to take-up horizontal loads caused by thelandslide pressure of the soil on the foundation wall which is incontact with the levelled ravine slope.

In another embodiment of the invention, transversal walls connected to alongitudinal wall are substantially parallel with each other and areinscribed in an imaginary rectangle in the plan view.

This embodiment of the invention makes it possible to erect a buildingthe form of which does not depend on the form of an arch foundation.Furthermore, in case of weak soils in the area of contact between thefoundation end faces and the ravine slopes this embodiment allows thetying-up of the arch (i.e. the interconnection of its ends) to be madewithin the plan outlines of the building.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will becomeapparent from the following detailed description, when taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates a plan view of a foundation of a building orinstallation, according to the invention;

FIG. 2 is a sectional view taken along line II--II in FIG. 1;

FIG. 3 is a plan view of an embodiment of a foundation of a building orinstallation, according to the invention;

FIG. 4 is a sectional view taken along line IV--IV in FIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

A foundation 1 (FIG. 1) is installed across a ravine and is of abox-shaped cross-section. The end faces of the foundation 1 bear againstopposite slopes 2, 3 of the ravine, the foundation 1 comprising twoupright arcuate longitudinal walls parallel with each other, namely anexternal wall 4 and an internal wall 5 having its camber directedtowards a higher ravine point. The foundation 1 is in the form of anarch in the horizontal plane. The walls 4 and 5 are interconnected witheach other by transversal vertical walls 6 and floors 7. The externalwall 4 is in contact with the levelled ravine slope to function asretaining wall and to keep the ravine soil disposed behind the wall 4 inthe equilibrium condition. The walls 4 and 5 may be prefabricated orcast-in-place. The choice of the walls mainly depends on the loadtaken-up by the foundation 1 and economical considerations.

When a horizontal pressure is applied to the wall 4, it is transmittedthrough the wall 6 and floors 7 to the wall 5. Furthermore, the walls 4and 5 are also under the vertical pressure from the building weight. Dueto this, it is possible to considerably reduce thickness of the walls 4,5 and 6. With considerable vertical loads under the walls 4 and 5,considerable stresses develop in the soil. To reduce these stresses,spreading pads 8 may be installed under the walls 4 and 5.

When the foundation of a building or installation is under a horizontalload P, the force which is applied to the end faces of the arch 1 isdecomposed into two components, one component P₁ being parallel to theslope 2, 3 of the ravine and the other component P₂ being directedacross the slope.

The walls 4, 5 and 6 and the floors 7 form a hollow structure whoseinterior may be used, e.g. for accommodation of garages or otherpurposes.

When several buildings are erected along the ravine, the backfilling ofa terrace 9 (FIG. 2), e.g. for sporting grounds or for placingengineering lines may be carried out between the buildings. The terrace9 may also be erected when only one building is constructed along theravine.

Erection of the structures is carried out in the following order: first,excavation of the soil of the base for the walls 4 and 5 is carried out,the walls 4 and 5 are then erected with concurrent erection andconcreting of the walls 6.

FIGS. 3, 4 show an embodiment of a foundation according to the inventionin which a foundation 1 comprises one longitudinal vertical wall 4connected to transversal vertical walls 6 disposed substantially inparallel with each other. The walls 6 are inscribed in an imaginaryrectangle in the plan view. The length of the foundation 1 may be equalto the length of the building, longer or shorter than the building. Thevalue of the rise of the arch foundation 1 may be equal to, greater orless than the width of the building. The building may be erected eithercontinuously or in an interrupted fashion along the foundation 1.

In the design according to the invention, the foundation 1 is buried inthe base and the transversal walls 6 disposed at the end faces of thewall 4 bear against the slopes 2, 3 of the ravine and are buried inthem. The walls 4, 6 may be prefabricated or cast-in-place depending onthe load and economical considerations.

To minimize shearing forces at the base, the design may involve thefoundation 1 which is not buried in the bedrock. Under the horizontalpressure from the backfilling and the walls 6 exerted on the foundation1, compressive forces develop in the foundation 1 which are transmittedby the end faces of the foundation 1 to the slopes 2, 3 of the ravine.In case of weak soils of the slopes 2, 3 of the ravine which are notcapable of taking-up a strong thrust from the foundation 1, its tying-upcan be carried out within the plan outlines of the building.

In spanning the walls 6 spaces are formed which can be used toaccommodate, e.g. garages.

Erection of structures is carried out in the following order.

First, levelling of the base for the foundation 1 is carried out. Thefoundation 1 is then erected or concreted. The floors 7 are theninstalled in the space between the walls 6 and the structures areerected above the foundation of the building or installation.

INDUSTRIAL APPLICABILITY

The present invention may be most effectively used in the development ofnonused territories or territories of limited use complicated by ravinesor hollows.

We claim:
 1. A foundation of a building or installation erected across aravine extending along a slope and having face ends bearing againstopposite slopes of the ravine, said foundation comprising a verticallyextending longitudinal wall and vertically extending transverse wallsconnected to said longitudinal wall, said longitudinal wall beingarcuate with a camber facing towards a higher ravine point,characterized in that said transverse walls are substantially parallelwith each other and are inscribed in an imaginary rectangle in the planview.